More than 20 cities, states and provinces from the United States and China formed an alliance on Tuesday in Los Angeles to implement ambitious and verifiable actions to address climate change and to support and expand bilateral cooperation and dialogue.

The sub-national leaders for the first time convened and issued a US-China Climate Leaders' Declaration at the first US-China Climate-Smart/Low-Carbon Cities Summit, also known as the US-China Climate Leaders Summit, on Wednesday and Thursday, a week ahead of Chinese President Xi Jinping's state visit to the US.

"We, the leaders of States, Provinces, Cities and Counties in China and the United States intend to take enhanced actions to mitigate carbon emissions, increase climate resilience, share experience, and strengthen bilateral cooperation," says the declaration.

The actions are intended to support the achievement and implementation of each country's respective post-2020 national climate targets and enhanced actions announced by US President Barack Obama and Xi in the historic November 2014 Joint Announcement on Climate Change, and in each country's Intended Nationally Determined Contribution (INDC).

The participating leaders on both sides also aim to accelerate the long-term transition to low-carbon economies, mindful of the goal of limiting global temperature increases to 2 degrees Celsius.

"Climate change is not only a common challenge for China and the US, but also a shared opportunity to strengthen cooperation in developing a green and low-carbon economy," said Xie Zhenhua, China's special representative for climate change.

He said the summit would serve as a new start for both countries to enhance their pragmatic collaboration in low-carbon cities, low-carbon technologies, the low-carbon market and other related areas.

"We often hear the phrase ‘Think globally and act locally.' Today's gathering is a great example of that," Vaughan Turekian, science and technology adviser to the secretary of state, said in addressing the summit.

The people who gathered here are day-to-day implementers at different levels and in various areas, such as governors, mayors, business leaders and innovators, who seek a path to a sustainable future and "have the will to make it happen", he said.

Among the participating leaders were 11 governors and mayors from Beijing, Sichuan province, Hainan province, Shenzhen, Wuhan, Guangzhou, Guiyang, Zhenjiang, Jinchang, Yan'an and Jilin; the California and Connecticut governors; and the mayors of Los Angeles, Houston, Seattle, Atlanta, Carmel, Phoenix, Salt Lake City, Miami and Des Moines.

In signing the declaration, the US and Chinese cities and states announced their targets to reduce emissions and establish climate-action plans to trim emissions and enhance bilateral partnerships and cooperation. 

For instance, California is committed to cutting emissions by 80 percent to 90 percent below 1990 levels by 2050, and Seattle pledges to become carbon-neutral by 2050, producing no net greenhouse gas emissions. 

Beijing and Guangzhou have committed to peak their carbon dioxide emissions by the end of or around 2020 – 10 years earlier than the national target – and the Chinese cities and provinces making commitments represent approximately 1.2 gigatons of annual carbon dioxide emissions, about 25% of China's urban total and roughly the same level of carbon dioxide emissions as Japan or Brazil. 

The declaration also features new initiatives, such as China's formulation of the new Alliance of Peaking Pioneer Cities (APPC). All cities and provinces in the alliance have for the first time established peak years for carbon dioxide emissions that are earlier than the national goal to peak around 2030.

Nine agreements or Memorandums of Understanding (MoU) were signed between the two sides, including an MoU between Los Angeles0 and Shenzhen and Guangzhou to share best practices and lessons learned in reducing emissions, and an arrangement between Los Angeles and Beijing to cooperate in low-carbon urban planning and transportation.

Los Angeles and Zhenjiang, in Jiangsu province, also announced that they have become the first cities to endorse the Sub-national Global Climate Leadership MoU – an effort led by California Governor Jerry Brown under which the two cities commit to either reducing greenhouse gas emissions 80 percent to 95 percent below 1990 levels by 2050 or achieving a per capita annual emission target of less than 2 metric tons by 2050.

The "Under 2 MOU" is expected to provide a template for the world's nations, states and cities to follow as work continues toward an international agreement to reduce greenhouse gas emissions ahead of December's United Nations Climate Change Conference in Paris.